我国五大湖三角帆蚌群体ITS-1序列变异分析

对我国五大淡水湖:鄱阳湖、洞庭湖、太湖、巢湖、洪泽湖,鄱阳湖内包括进贤、余干、珠湖、都昌、湖口、永修,合计10个群体三角帆蚌78个个体核糖体DNA基因转录间隔子ITS-1进行PCR扩增、序列测定,获得78条长度为430 bp的同源序列.同源基因序列分析显示,五大淡水湖10个群体三角帆蚌78条ITS-1序列片段,G C的含量都明显高于A T的含量.都阳湖三角帆蚌的核苷酸多态性指数最高,而巢湖的核苷酸多样性指数最低.基于ITS-1序列片段的遗传距离表明,鄱阳湖内六个点群体间遗传距离很小,在0.071到0.0092之间.五大湖间三角帆蚌群体遗传距离较远,在0.0752到O.1381之间.ITS-1序列片段构建系统树显示,鄱阳湖6个群体聚在了一起为单独一支,并与巢湖群体亲缘关系相近.洞庭湖群体和洪泽湖群体亲缘关系相近,单独为一支.太湖群体从都阳湖、巢湖群体分离开来,单独为一支.     

广东流溪河水库异尾轮属(Trichocerca)的分布模式及其影响因素

异尾轮虫是热带亚热带地区轮虫的重要优势类群.为了解其在水库中的分布模式和潜在影响因素,于2013-2014年对广东流溪河水库河流区、过渡区及湖泊区的异尾轮虫群落及环境因子进行逐月调查.2年共采集到异尾轮虫11种,其中对棘异尾轮虫(Trichocerca similis)、圆筒异尾轮虫(T.cylindrica)、暗小异尾轮虫(T.pusilla)和刺盖异尾轮虫(T.capucina)为优势种,主要出现在丰水期,具有明显的季节分布模式.2013-2014年河流区、过渡区和湖泊区异尾轮虫丰度平均值分别为142.9、102.5和53.6 ind./L,3个水域的异尾轮虫总丰度在夏季(5-9月)较高.从水库上游到下游,异尾轮属的物种丰富度和Simpson多样性指数呈现递减趋势,体现了群落对环境的分区和稳定性变化的响应.群落丰度组成的主成分分析表明,主要优势种的丰度全年分布差异较大,而多数种类全年分布差异小.冗余分析表明,叶绿素a浓度、晶囊轮虫丰度、水温+磷酸盐浓度分别为影响河流区、过渡区和湖泊区异尾轮虫群落结构的关键变量,而降雨则是影响整个库区异尾轮虫群落结构的潜在变量.     

中国蓝藻的新记录属——双囊藻属(Geminocystis)及分类和生态学讨论

现代分子生物学技术为蓝藻的生物多样性研究提供了更多信息和证据.单细胞蓝藻——双囊藻属（Geminocystis）是2009年从集胞藻（Synechocystis）分离出来的新属.2017年5月从青海湖的封闭子湖——月牙湖采集分离到一株单细胞蓝藻藻株,16S rRNA基因序列显示此藻株和双囊藻的藻种显示出最高的相似性,都在97%以上,并且在分子系统树聚为一束.此株的细胞结构以及超微结构显示,细胞纵轴具有窝式结构以及类囊体不规则的排列等双囊藻属所具有的特征.双囊藻是我国蓝藻的新报道纪录属,本研究还对双囊藻的分类和生态进行了讨论.     

五个湖泊中华刺鳅(Mastacembelus sinensis)种群线粒体细胞色素b遗传多样性分析

采用特异性引物对中华刺鳅基因组DNA进行扩增和测序,获得了江苏省5个湖泊的中华刺鳅种群线粒体cyt b基因767 bp的序列.分析表明,cyt b基因中A+T含量略高于G+C含量,144个中华刺鳅共获得cyt b基因单倍型28个,变异位点38个,其中单倍型Hap1分布最为广泛,可能为祖先型单倍型.平均单倍型多样性和平均核苷酸多样性指数分别为0.58751和0.00214,遗传多样性较低.群体间遗传分化系数为0.0356,绝大多数的遗传变异都来自群体内部,而群体间的遗传分化极小.构建的系统进化树未出现明显的以单个湖泊群体的聚簇,5个湖泊的种群间基因交流极其强烈.研究结果表明,当前5个湖泊的中华刺鳅遗传多样性水平比较低,亟待加强保护.     

城市河流细菌群落特征及影响因素——以鄱阳湖流域赣江南昌段为例

为了了解赣江细菌群落特征,探讨环境因子对城市河流细菌群落结构组成的影响,本文基于高通量测序分析鄱阳湖流域赣江南昌段2015年4月至2016年3月5个采样点(G1~G5)的细菌群落特征.采用R语言"Vegan"程序包中的"Bioenv"程序、冗余分析方法分析环境因子对河水细菌群落的影响,基于Bayesian统计方法的Source Tracker模型估算南昌城区对赣江细菌群落的改变比例.结果表明:赣江南昌段的优势菌门为放线菌门(Actinobacteria,34.05%)和变形菌门(Proteobacteria,31.59%),其次为厚壁菌门(Firmicutes,15.49%)和拟杆菌门(Bacteroidetes,9.12%);气温和流量是河流细菌群落主要影响因子,其中气温是影响OTU丰度的最佳单参数,影响门丰度的最佳单参数是流量;水文气象条件(气温和流量)对河流细菌群落的影响大于水化学指标,包括营养盐(溶解有机碳、总磷和铵态氮)、水化学离子(HCO_3~-、Cl~-、NO_3~-、SO_4~(2-)、Na~+、K~+和Mg~(2+))和重金属元素(Mn、Cd、Cr、Pb、Cu、As、Ba和Fe).除Proteobacteria外,其余门的细菌相对丰度在5个采样点之间不存在显著差异;Source Tracker模型结果表明南昌城区对赣江细菌群落结构组成的影响为6.33%~34.67%,对赣江南支细菌群落的影响显著高于其他河段;南昌城区对细菌群落的影响较小,主要的影响门类为Proteobacteria.     

Commentaries on “Evaluating the Geographic in GIS”

In this article, four geographers who are also GIS practitioners critique “Evaluating the Geographic in GIS.” Sparked by the arguments in that article, they pose fundamental questions about how geography can best contribute to GIS practices.     

多样性视角下的城市复合功能特征及成因探测——以长春市为例

多功能要素的复合化已成为信息时代城市空间发展的重要趋势,而复合功能开发亦被认为是解决城市交通拥堵、低效能源消耗及职住不平衡等问题的重要手段,对促进有活力的、宜居的及可持续的城市环境建设具有重要意义。基于城市多样性的理论框架,在界定城市功能复合内涵的基础上,以长春市中心城区城市功能兴趣点（POI）数据为基础,采用区位熵指数、信息熵指数及地理探测器模型,分析城市居住、办公、商业、休闲四类功能要素的复合特征,并探讨城市功能复合空间分异的驱动因素。结果表明：① 城市功能要素集中度特征显著,各类型功能要素均形成了专业化的功能集聚区,但各区块间功能要素的专业化程度存在较大差异。② 城市功能要素复合度整体表现出核心—边缘的空间差异,核心区街道复合度整体高于外围开发区,办公、商业、休闲三种功能要素间的复合度要整体强于其各自与居住功能的复合。③ 以单一功能为主、多功能兼容的综合型复合是街道尺度功能复合的主要表现形式;各功能要素中,休闲、商业功能具有较强的兼容性。④ 城市功能复合的空间异质性特征显著,土地价格、休闲要素数量是造成多功能复合分异的主要原因;分类型复合中,各解释因子影响力度表现各异。     

河北承德双塔山滦河国家湿地公园水鸟多样性及其季节分布规律

2017年11月至2018年11月,采用样线法和定点观察法,对河北承德双塔山滦河国家湿地公园中的水鸟进行了调查,共记录水鸟29种,隶属6目8科21属。其中,有国家二级保护鸟类3种,列入《世界自然保护联盟濒危物种红色名录》近危物种2种,易危物种4种,河北省省级重点保护野生动物9种。在29种水鸟中,雁形目和鸻行目水鸟的物种数分别占该湿地公园水鸟总物种数的44.83%和27.59%;雁形目水鸟种群数量占该湿地公园水鸟个体总数的91.51%。2018年4月,水鸟物种数量最多,为14种,水鸟群落的多样性指数最高,为1.911 5;5月,水鸟群落的均匀度指数最高,为0.858 4;2018年10月,水鸟种群数量最多,为250只。从水鸟的居留型来看,以旅鸟为主,其数量占水鸟个体总数的82.76%,夏候鸟的数量占10.34%,留鸟的数量占6.9%。调查期间,水鸟主要分布在湿地公园内的一道坝与三道坝之间的开阔水域中。     

Genetic Diversity of Toona ciliata Populations based on SSR Markers

In order to provide a theoretical basis for the protection and development of T. ciliata germplasm resources, we studied the genetic diversity of T. ciliata by using SSR (Simple Sequence Repeat) primers to evaluate the genetic diversity of 192 T. ciliata germplasm samples from 24 populations of 5 provinces. DataFormater, Popgene, NTSYS, TFPGA and other software were used for genetic data conversion, genetic parameter estimation, dendrogram construction and genetic variation analysis. The results showed that: 1) a total of 17 alleles (N_a) were detected in seven pairs of primers, with an average of 2.260 for each primer. Among them, the highest numbers of alleles (4) were detected in primers S11 and S422.The mean value of Nei’s genetic diversity index (H) was 0.4909, the mean value of Shannon information index (I) was 0.7321, and the mean value of polymorphic information content (PIC) was 0.5182. The mean expected heterozygosity (H_e) and observed heterozygosity (H_o) were 0.1055 and 0.4956, respectively. The Nei°s genetic distances of the populations ranged between 0.0002 and 2.6346, and the mean was 0.5477. The average genetic diversity level (H=0.1044) of the 24 populations was lower than that of the species (H=0.4909). 2) The genetic differentiation coefficients (F_st) varied from 0.2374 to 0.9148, with an average value of 0.7727. The mean of population gene flow (N_m) was 0.0735, indicating a low level of genetic exchange between populations, and suggesting that the genetic variation mainly came from within populations. 3) With the UPGMA method, the 24 populations were clustered into 3 groups at Nei’s genetic identity (0.99): the populations from Guizhou Province and Guangxi Zhuang Autonomous Region were clustered into one group, the populations from Hunan Province were in another group, and the populations from Hubei Province were in the third group. The Mantel test analysis showed a significant correlation between Nei’s genetic distance and geographic distance (r=0.6318, P=0.009?0.05). The genetic diversity of the 24 populations of T. ciliata was at a low level. Geographic isolation was the main reason for genetic differentiation among T. ciliata provenances. In the protection of germplasm resources of T. ciliata, emphasis should be placed on breeding genetic resources from the populations with higher genetic diversity (P14, for example). As for the populations with low genetic diversity, an ex-situ protection strategy as well as ecological and timber objectives, should be taken into account to maximize the conservation and utilization of the diversity of T. ciliata.     

Blooms of Prorocentrum donghaiense reduced the species diversity of dinoflagellate community

Most of reported harmful algal blooms(HABs)of microalgae(75%)have been caused by dinoflagellates.Studies on the negative effects of HABs have generally focused on animals,valuable organisms in particular,and environmental factors such as dissolved oxygen and nutrients,but relatively fewer on community level,particularly that using metagenomic approach.In this study,we reported an investigation on the effects of a HAB caused by the dinoflagellate Prorocentrum donghaiense on the species diversity and community structure of the dinoflagellate sub-community via a pyrosequencing approach for the samples taken before,during,and after the bloom season of P.donghaiense in the East China Sea.We sequenced partial 28S rRNA gene of dinoflagellates for the field samples and evaluated the species richness and diversity indices of the dinoflagellate community,as a sub-community of the total phytoplankton.We obtained 800185 valid sequences(categorized into 560 operational taxonomic units,OTUs)of dinoflagellates from 50 samples and found that the biodiversity of dinoflagellate community was significantly reduced during the blooming period in comparison to that in pre-and after-blooming periods,as reflected in the four diversity indices:the species richness expressed as the number of OTUs,Chao1 index,Shannon index(evenness),and Gini-Simpson index.These four indices were all found to be negatively correlated to the cell density of the bloom species P.donghaiense.Correlation analyses also revealed that the P.donghaiense cell abundance was correlated negatively with NO3--N,and NO2--N,but positively with total nitrogen(TN)and total phosphorus(TP).Principal coordinates analysis(PCoA)showed that the community structure of dinoflagellates was markedly different among the different sampling periods,while the redundancy analysis(RDA)revealed P.donghaiense abundance,salinity,NO3--N,and SiO32-were the most four significant factors shaping the dinoflagellate community structure.Our results together demonstrated that HABs caused by the dinoflagellate P.donghaiense could strongly impact the aquatic ecosystem on the sub-community level which the blooming species belongs to.